JP2008266628A - Phosphor particle dispersion, and three-dimentional display device and two-dimentional display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphor particle dispersion which uses a phosphor particle exhibiting upconversion emission, is enabled to enlarge and to easily produce and has excellent transparency, providing also a three-dimentional display device and a two-dimentional device, as a main purpose. <P>SOLUTION: The dispersion is obtained by dispersing the phosphor particles which exhibit upconversion emission by being excited with light in the range of 700-2,000 nm of a wavelength, into a transparent liquid or a transparent resin, wherein the refractive index of the particle is substantially same as that of the transparent liquid or the transparent resin. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a phosphor particle dispersion and a three-dimensional display device that use phosphor particles that emit up-conversion light and can be suitably used in the medical field, architectural field, air traffic control system, molecular structure display, and the like. Is. The present invention also relates to a phosphor particle dispersion and a two-dimensional display device that use phosphor particles that emit up-conversion light and can be suitably used in information display fields such as in-vehicle displays. .

  It is indispensable to handle three-dimensional information in many fields such as CT diagnosis and surgical simulation in the medical field, CAD in the building field, aircraft position display in air traffic control systems, and molecular structure display in science and technology calculations. Currently, CRT (CRT) displays, liquid crystal displays, electroluminescence displays, etc. are known as display devices capable of three-dimensional display, but since these displays can only display two-dimensional images, perspective methods are used. 3D display is made possible by the pseudo 3D display method. However, it is difficult for the pseudo three-dimensional display method to sufficiently display the three-dimensional information as described above. Therefore, there is a demand for a three-dimensional display device that displays a large amount of three-dimensional information at a high speed and can be observed freely from front and rear, left and right, and top and bottom.

In general, the physiological factors that cause a human to stereoscopically view an object are called (1) binocular parallax, (2) binocular congestion angle, (3) focus adjustment (crystal adjustment), and (4) monocular motion parallax. .
Conventionally, most of the methods used for three-dimensional display realize (1) binocular parallax, and must be accompanied by unnaturalness and extreme fatigue. It is also thought to be a cause of physiological diseases such as anomalies in stereoscopic perception. Recently, attempts have been made to superimpose a plurality of flat screens to satisfy (2) the binocular congestion angle, and (3) focus adjustment (adjustment of the lens), but this is not sufficient. Also, (4) monocular motion parallax has not yet been realized.

  A display device using holography is well known as a display device that displays a stereoscopic image more faithfully. Holography can satisfy the above three points: (1) binocular parallax, (2) binocular congestion angle, and (3) focus adjustment (crystal lens adjustment), but (4) monocular motion parallax. Realization is difficult. In addition, a display device using holography needs to perform optical writing and reproduction, and when displaying an electronic fictitious object, it is necessary to perform calculation of a huge amount of interference fringes. It is very difficult to display.

  Moreover, a volume scanning method (depth sampling method) is mentioned as a method which satisfies said (1)-(4). The volume scanning method is a method for displaying a complete three-dimensional image in a true sense, that is, it can be observed freely from front to back, left and right, and top and bottom. As for the volume scanning method, (a) varifocal mirror method, (b) moving display method, (c) moving screen method, and (d) up-conversion fluorescence method are known.

  The (a) varifocal mirror method is a method in which an image of a cathode ray tube or the like is reflected in synchronization with the movement of a mirror that vibrates back and forth. However, an oscillating mirror changes the magnification of the image and requires correction. In addition, there is a limit to the size that can be expressed and the range in which the image can be seen.

  The (b) moving display system displays a stereoscopic image by moving and rotating a light emitting diode display or the like displaying a cross-sectional view of a stereoscopic image at high speed. Further, the above (c) moving screen system is to make a moving image appear three-dimensionally by drawing a cross-sectional view of a three-dimensional image with laser light on a moving screen. However, these methods have a problem that the range in which a stereoscopic image can be seen is limited depending on the direction of movement, and the resolution is different. In addition, the structural member of the three-dimensional display device must be included in the display unit, and the image tends to become unclear basically.

The above (d) up-conversion fluorescence method uses the up-conversion phenomenon of the phosphor, and particularly uses the up-conversion phenomenon due to two-stage absorption to cause the phosphor to emit light along the actual light emitting surface, thereby producing a three-dimensional image. (For example, refer to Patent Document 1 and Non-Patent Document 1).
In Non-Patent Document 1, a fluorescent glass deposited on a fluoride glass is used as a display unit. Laser beams having two different wavelengths are incident on the display unit from different directions and intersected at a single point. A method of emitting light has been proposed. In this method, a three-dimensional image can be displayed because the light emission point moves by scanning in the horizontal and vertical directions while synchronizing the respective laser beams.
However, the display unit is formed by depositing a phosphor on fluoride glass, and it is difficult to manufacture a large display unit. Moreover, there is a possibility that the emission color may be affected by the composition of the fluoride glass, and the target emission color may not be obtained. Furthermore, in order to display a stereoscopic image with a plurality of emission colors, that is, to display a stereoscopic image in color, a phosphor that emits only three primary colors of monochromatic light is selected, and a fluoride glass on which each phosphor is deposited is selected. It is necessary to manufacture and laminate these to form a display portion, and the manufacturing process is complicated. For this reason, it has not reached practical use.

  Therefore, the present inventor, as a three-dimensional display device that can be increased in size and easily manufactured, converts fluorescent fine particles that are excited by two or more different wavelengths of light to emit up-conversion light into a transparent liquid or a transparent resin. A three-dimensional display device having a display unit using a dispersed phosphor fine particle dispersion was proposed (see Patent Document 2).

  Further, in a two-dimensional display device that displays a two-dimensional image, the use of the phosphor up-conversion phenomenon has attracted attention. Conventionally, phosphors that emit visible light when excited by ultraviolet rays have been used in CRT displays, plasma displays, and the like. On the other hand, the phosphor that emits up-conversion light emits visible light when excited by infrared rays. Infrared rays are advantageous in terms of safety and cost as compared with ultraviolet rays. For this reason, it is expected that the phosphor up-conversion phenomenon is used in the two-dimensional display device.

For example, Patent Document 3 proposes crystallized glass in which phosphor crystals are precipitated as a light-emitting material. However, since the phosphor is deposited on the glass, there is a problem as in Non-Patent Document 1.
Moreover, although it does not utilize the up-conversion phenomenon of the phosphor, for example, Patent Document 4 proposes to use an electroluminescence (EL) display as an in-vehicle display.

JP-T-2005-513885 JP 2006-249254 A JP-A-2005-206628 JP 2005-289183 A "A Three-Color, Solid-State, Three-Dimensional Display" Elizabeth Downing, Lambertus Hesselink, John Ralston, Roger Macfarlane, p.1185-1188, SCIENCE, Vol. 273, 30 August 1996.

  The display unit of the three-dimensional display device is preferably transparent from the viewpoint of display quality. However, in the method described in Patent Document 2, since the phosphor fine particles are dispersed in a transparent liquid or transparent resin, the transparency of the phosphor fine particle dispersion used in the display unit may be reduced by the phosphor fine particles. .

  Similarly, the display unit of the two-dimensional display device is preferably transparent from the viewpoint of display quality. For example, if crystallized glass on which the above-described phosphor crystals are deposited is used for a display portion, a transparent display portion can be obtained, but there are problems as described above. For example, when the above-mentioned EL display is used for the display unit, the EL display has a structure in which a transparent electrode, an insulating layer, a light emitting layer, an insulating layer, a transparent electrode, and a cover glass are sequentially laminated on a glass substrate. Therefore, in order to obtain a transparent display unit, high transparency is required for all the constituent members, and wiring or the like is usually visually recognized.

  The present invention has been made in view of the above problems, and uses phosphor particles that emit up-conversion light, and can be enlarged, easily manufactured, and excellent in transparency. A main object is to provide a particle dispersion, a three-dimensional display device, and a two-dimensional display device.

  In order to achieve the above object, the present invention provides a phosphor particle dispersion in which phosphor particles that are excited by light having a wavelength in the range of 700 nm to 2000 nm and emit up-conversion are dispersed in a transparent liquid or a transparent resin. The phosphor particle dispersion is characterized in that the refractive index of the phosphor particles and the refractive index of the transparent liquid or transparent resin are substantially the same.

When the phosphor particle dispersion of the present invention is used in a display device, an image can be displayed by utilizing an up-conversion phenomenon due to two-stage absorption of phosphor particles. Further, since the refractive index of the phosphor particles and the refractive index of the transparent liquid or transparent resin are substantially the same, the transparency of the phosphor particle dispersion can be improved, and a display device with excellent display quality can be obtained. it can.
Such a phosphor particle dispersion of the present invention is used, for example, in which phosphor particles are dispersed in a transparent liquid, or phosphor particles are kneaded in a transparent resin, or phosphor particles are used for forming a transparent resin. Since it can be produced by dispersing in a monomer and curing the monomer, it can be easily manufactured and can be enlarged. In addition, the transparent liquid and transparent resin used in the present invention can be arbitrarily selected, and it is possible to prevent the emission color from being affected by the composition of the medium in which the phosphor particles are dispersed, and the intended emission color. Can be obtained.

  In the said invention, it is preferable that the said fluorescent substance particle is excited by the light of 2 or more types of different wavelengths among the wavelengths in the range of the said 700 nm-2000 nm, and emits upconversion. When the phosphor particle dispersion of the present invention is used in a display device, a stereoscopic image can be displayed by utilizing an up-conversion phenomenon due to two-stage absorption of the phosphor particles. Further, since the refractive index of the phosphor particles and the refractive index of the transparent liquid or transparent resin are substantially the same, the transparency of the phosphor particle dispersion can be improved, and a display device having excellent display quality can be obtained. it can. Such a phosphor particle dispersion of the present invention is used, for example, in which phosphor particles are dispersed in a transparent liquid, or phosphor particles are kneaded in a transparent resin, or phosphor particles are used for forming a transparent resin. Since it can be produced by dispersing in a monomer and curing the monomer, it can be easily manufactured and can be enlarged. In addition, the transparent liquid or transparent resin used in the present invention can be arbitrarily selected, and it is possible to prevent the emission color from being affected by the composition of the medium in which the phosphor particles are dispersed, and to achieve the target emission color. It is possible to obtain Furthermore, when the phosphor particle dispersion of the present invention is applied to a three-dimensional display device capable of color display, for example, a fluorescence in which a plurality of phosphor particles exhibiting different emission colors are dispersed in a transparent liquid or a transparent resin. A body particle dispersion may be used. Therefore, it is possible to easily obtain a phosphor particle dispersion that can be used in a three-dimensional display device for color display.

  In the said invention, it is preferable that the said fluorescent substance particle contains rare earth elements and the base material of the said fluorescent substance particle is a halide. This is because the phosphor particles containing rare earth elements emit light stably and exhibit sufficient luminous efficiency, and there is no problem of lack of stability during storage unlike organic phosphors. Furthermore, many rare earth elements have a plurality of energy levels in an excited state, and are suitable as those that are excited by light of two or more different wavelengths and emit up-conversion. Further, when the phosphor particle base material is a halide, the luminous efficiency is further improved.

  In this case, the rare earth element is erbium (Er), holmium (Ho), praseodymium (Pr), thulium (Tm), neodymium (Nd), gadolinium (Gd), europium (Eu), samarium (Sm), terbium ( It is preferably at least one or more rare earth elements selected from the group consisting of Tb), dysprosium (Dy), and cerium (Ce). This is because these are preferable as rare earth elements capable of up-conversion emission.

  Moreover, it is preferable that the phosphor particle dispersion of the present invention is used in a display unit of a three-dimensional display device. Since the phosphor particle dispersion of the present invention has high transparency, as described above, the phosphor particle dispersion of the present invention is used for the display unit of the three-dimensional display device, thereby providing a three-dimensional display device having excellent display quality. Because it can be obtained.

  In the above-mentioned invention, it is also preferred that the phosphor particles emit up-conversion light by being excited by light of one wavelength among the wavelengths in the range of 700 nm to 2000 nm. When the phosphor particle dispersion of the present invention is used in a display device, an image can be displayed by utilizing an up-conversion phenomenon due to two-stage absorption of phosphor particles. Further, since the refractive index of the phosphor particles and the refractive index of the transparent resin are substantially the same, the transparency of the phosphor particle dispersion can be improved, and a display device excellent in display quality can be obtained.

  In the said invention, it is preferable that the said fluorescent substance particle contains rare earth elements and the base material of the said fluorescent substance particle is a halide. This is because the phosphor particles containing rare earth elements emit light stably and exhibit sufficient luminous efficiency, and there is no problem of lack of stability during storage unlike organic phosphors. Further, the rare earth element can be excited by light of one kind of wavelength to emit up-conversion light. Further, when the phosphor particle base material is a halide, the luminous efficiency is further improved.

  In this case, the rare earth element is erbium (Er), holmium (Ho), praseodymium (Pr), thulium (Tm), neodymium (Nd), gadolinium (Gd), europium (Eu), samarium (Sm), terbium ( It is preferably at least one or more rare earth elements selected from the group consisting of Tb), dysprosium (Dy), and cerium (Ce). This is because these are preferable as rare earth elements that can be excited by light of one wavelength and emit up-conversion light.

  In the above case, the phosphor particles preferably further contain ytterbium (Yb). This is because ytterbium (Yb) has good sensitivity to light and functions as a sensitizer. Further, when the energy levels of ytterbium (Yb) and the rare earth element are close, energy transfer occurs, which is advantageous for up-conversion light emission using light of one wavelength.

  The phosphor particle dispersion of the present invention is also preferably used for a display unit of a two-dimensional display device. Since the phosphor particle dispersion of the present invention has high transparency, as described above, the phosphor particle dispersion of the present invention is used for the display unit of the two-dimensional display device, thereby providing a two-dimensional display device having excellent display quality. Because it can be obtained.

  Furthermore, the present invention controls the display unit having the phosphor particle dispersion described above, two or more infrared light sources arranged around the display unit, and the direction of light emitted from the infrared light source. And a control means for providing a three-dimensional display device.

  According to the present invention, since the phosphor particle dispersion described above is used in the display unit, the transparency is high and a good image display can be obtained. In addition, the display portion can be enlarged. Furthermore, as described above, in the phosphor particle dispersion, the medium in which the phosphor particles are dispersed can be arbitrarily selected, so that it is possible to prevent the emission color from being affected by the composition of the medium. Further, in the case of a three-dimensional display device capable of color display, the phosphor particle dispersion can be easily manufactured, so that a display portion can be easily obtained.

  The present invention also provides a display unit having the above-described phosphor particle dispersion, an infrared light source that projects infrared light on the display unit, and a control unit that controls the direction of light emitted from the infrared light source. A two-dimensional display device is provided.

  According to the present invention, since the phosphor particle dispersion described above is used in the display unit, the transparency is high and a good image display can be obtained. In addition, the display portion can be enlarged. Furthermore, as described above, in the phosphor particle dispersion, the medium in which the phosphor particles are dispersed can be arbitrarily selected, so that it is possible to prevent the emission color from being affected by the composition of the medium.

  Since the phosphor particle dispersion of the present invention is excellent in transparency, the display quality is improved, the size can be increased, and it can be easily manufactured. In addition, a transparent liquid or a transparent resin in which the phosphor particles are dispersed can be arbitrarily selected, and it is possible to avoid the influence of the emission color of the up-conversion emission by the composition of the medium, thereby obtaining a target emission color. There is an effect that can be. Furthermore, the phosphor particle dispersion of the present invention can be suitably used for a three-dimensional display device capable of color display or a two-dimensional display device.

  Hereinafter, the phosphor particle dispersion, the three-dimensional display device, and the two-dimensional display device of the present invention will be described in detail.

A. Phosphor particle dispersion The phosphor particle dispersion of the present invention is a phosphor in which phosphor particles that are excited by light having a wavelength in the range of 700 nm to 2000 nm and up-converted light are dispersed in a transparent liquid or transparent resin. In the particle dispersion, the refractive index of the phosphor particles and the refractive index of the transparent liquid or transparent resin are substantially the same.
The phosphor particle dispersion of the present invention is one in which the phosphor particles are excited by two or more different wavelengths of light within a wavelength range of 700 nm to 2000 nm to emit up-conversion, or 1 It can be divided into two embodiments depending on whether it is excited by light of a specific wavelength to emit up-conversion light. In the following, each embodiment will be described separately.

I. 1st embodiment 1st embodiment of the fluorescent substance particle dispersion of this invention is phosphor particle which is excited by the light of two or more different wavelengths among the wavelengths in the range of 700 nm-2000 nm, and emits upconversion light. A phosphor particle dispersion dispersed in a transparent liquid or transparent resin, wherein the refractive index of the phosphor particles and the refractive index of the transparent liquid or transparent resin are substantially the same. is there.

The up-conversion light emission in this embodiment will be described with reference to the drawings. FIG. 1 shows an example in which erbium (Er) is used as a rare earth element and infrared light of 1500 nm and 850 nm is irradiated as excitation light. First, as shown in FIG. 1A, erbium is excited by the excitation light of 1500 nm and _moves from ¹ I _15/2 to ¹ I _13/2 having a higher energy level. As shown in FIG. 1B, erbium is excited by 850 nm excitation light, and the energy level of erbium is further _increased from ¹ I _13/2 to ⁴ S _3/2 . Then, as shown in FIG. 1C, when the excited erbium returns to the ground state, light of 545 nm is emitted.

  As described above, in this embodiment, the case where the light excited at 1500 nm and 850 nm emits light having a higher energy of 545 nm, that is, the case where light emitted at a higher energy than the excitation light is emitted as up-conversion light emission. That's it.

  Since the phosphor particles in the present embodiment contain, for example, a rare earth element that generates such up-conversion light emission, it is not necessary to excite with high energy light such as ultraviolet light. In addition, when the phosphor particle dispersion according to this embodiment is used in, for example, a display device, it is usually preferable that light emission is visible light. Therefore, in the case of up-conversion emission, light having a wavelength longer than that of visible light is used as excitation light. For this reason, the excitation light wavelength and the emission wavelength hardly overlap each other, and a good image display can be obtained.

In addition, the phosphor particles in the present embodiment emit up-conversion light by being excited by light of two or more different wavelengths. That is, the phosphor particles are excited by two excitation light of the infrared light 2 of the infrared light 1 and the wavelength lambda ₂ wavelength lambda ₁ as illustrated in FIG. 2, to emit light having a wavelength lambda ₃ Can do.
As described above, up-conversion emission by two-stage absorption is referred to in the present embodiment when the up-conversion emission is excited through the energy level by two or more types of excitation light having different wavelengths.

FIG. 3 shows a three-dimensional display device using a phosphor particle dispersion obtained by dispersing phosphor particles exhibiting up-conversion emission exemplified in FIG. 2 in a transparent resin. As illustrated in FIG. 3, infrared light 15 a having a wavelength λ ₁ (infrared light 1 in FIG. 2) is irradiated from one direction of the display unit 11 made of the phosphor particle dispersion according to the present embodiment, and another direction 2 is irradiated with infrared light 15b having a wavelength λ ₂ (infrared light 2 in FIG. 2) and crossed at one point. Then, the point 13 where the infrared light 15a (infrared light 1 in FIG. 2) and the infrared light 15b (infrared light 2 in FIG. 2) intersect emits light. This is because up-conversion emission exemplified in FIG. 2 occurs at this time. When the infrared light 15a and the infrared light 15b are scanned in the horizontal and vertical directions while synchronizing the infrared light 15a and the infrared light 15b, the light emission point 13 moves three-dimensionally, so that a three-dimensional image can be displayed.

  In this embodiment, since the refractive index of the phosphor particles and the refractive index of the transparent liquid or transparent resin are substantially the same, the transparency of the phosphor particle dispersion can be improved. Therefore, when the phosphor particle dispersion according to this embodiment is used in, for example, a display device, display quality can be improved.

  “The refractive index of the phosphor particles and the refractive index of the transparent liquid or transparent resin are substantially the same” means that the difference between the refractive index of the phosphor particles and the refractive index of the transparent liquid or transparent resin is ± 0.00. It is within 05. The difference between the refractive index of the phosphor particles and the refractive index of the transparent liquid or transparent resin is preferably within ± 0.03, more preferably within ± 0.01.

The “refractive index of the transparent resin” refers to the refractive index of the transparent resin constituting the phosphor particle dispersion. For example, when the transparent resin is a photocurable resin or a thermosetting resin and a monomer is used as a raw material for the photocurable resin or the thermosetting resin, the refractive index of the transparent resin is the It refers to the refractive index after curing of the monomer, not the refractive index.
Here, generally, the refractive index after curing of the monomer tends to be slightly higher than the refractive index of the monomer. However, the increase in the refractive index after curing of the monomer with respect to the refractive index of the monomer is such that the refractive index of the phosphor particles and the refractive index of the transparent resin are not substantially the same. If the refractive index of the monomer and the refractive index of the monomer that is the raw material of the transparent resin are substantially the same, it can be considered that the refractive index of the phosphor particles and the refractive index of the transparent resin are substantially the same. That is, it can be said that the refractive index of the phosphor particles and the refractive index of the transparent resin are substantially the same, the refractive index of the phosphor particles and the refractive index of the monomer that is the raw material of the transparent resin are substantially the same.
At this time, the difference between the refractive index of the phosphor particles and the refractive index of the monomer that is the raw material of the transparent resin is preferably within ± 0.05, more preferably within ± 0.03, and even more preferably ± 0. Within .01.

The refractive index of the phosphor particles is a value measured using an immersion method. The phosphor particles are placed in a refractive liquid (for example, Cargill standard refractive liquid: manufactured by Moritex Co., Ltd.), and light is applied from the side. As the refractive index of the refracting liquid is changed, the scattered light disappears and becomes transparent at a point that matches the refractive index of the phosphor particles. The refractive index of the phosphor particles is determined by the refractive index of the refractive liquid at this time. The refractive index is determined under natural light or white light.
The refractive index of the transparent resin is a value measured using a refractometer KPR-200 manufactured by Kalnew Optics, a refractometer PR-2 manufactured by Carl Zeiss Jena, and an Abbe refractometer NAR-1T SOLID manufactured by Atago. .
The refractive index of the transparent liquid is a value measured using a precision refractometer KPR-30V manufactured by Kalnew Optical.

  Furthermore, the phosphor particle dispersion of the present embodiment is obtained by dispersing the phosphor particles in a transparent liquid or transparent resin. For example, the phosphor particles are dispersed in the transparent liquid, or the phosphor particles are transparent resin. It can be produced by kneading in or by dispersing the phosphor particles in a monomer or the like used for forming a transparent resin and then curing the monomer. Therefore, it can be easily manufactured and can be increased in size.

  In addition, in the case where the phosphor is deposited on the fluoride glass described in the background art column, the medium on which the phosphor is deposited is limited, whereas in this embodiment, a transparent liquid or a transparent liquid that disperses the phosphor particles is used. The resin can be arbitrarily selected, and it is possible to prevent the emission color from being affected by the composition of the medium. Therefore, it is possible to obtain a target emission color.

  Furthermore, when the phosphor particle dispersion of this embodiment is applied to, for example, a three-dimensional display device capable of color display, each phosphor particle exhibiting upconversion emission at a wavelength corresponding to each of the three primary colors is transparent liquid or A phosphor particle dispersion dispersed in a transparent resin may be used. Therefore, it is possible to easily obtain a phosphor particle dispersion that can be used in a three-dimensional display device for color display.

  Hereinafter, each structure of the phosphor particle dispersion of this embodiment will be described.

1. Phosphor particles The phosphor particles in the present embodiment are preferably so-called activated phosphor particles in which an element that emits fluorescence is doped into a base material. This is because the intensity and color of light emission can be adjusted depending on the type of element and the amount of doping.

  At this time, as the fluorescent element contained in the phosphor particles, it is possible to emit up-conversion light by being excited by light of two or more different wavelengths, and by light having a wavelength within a predetermined range. There is no particular limitation as long as it is excited. This is because a three-dimensional display device using such a phosphor particle dispersion can display a stereoscopic image by utilizing the up-conversion phenomenon due to two-stage absorption of the phosphor particles.

  In this embodiment, the phosphor particles preferably contain a rare earth element. This is because many rare earth elements have a plurality of energy levels in an excited state, and are suitable as those that are excited by light of two or more different wavelengths and emit up-conversion light.

  The rare earth element used in this embodiment is not particularly limited as long as it is excited by light of two or more different wavelengths and emits up-conversion light. In general, rare earth elements that are trivalent ions can be mentioned, among which erbium (Er), holmium (Ho), praseodymium (Pr), thulium (Tm), neodymium (Nd), gadolinium (Gd), Europium (Eu), samarium (Sm), terbium (Tb), dysprosium (Dy) and cerium (Ce) are preferably used. These rare earth elements may be used alone or in combination of two or more.

As examples of the up-conversion emission of the rare earth element, FIGS. 4A to 4C show up-conversion emission of praseodymium (Pr), erbium (Er), and thulium (Tm), respectively. Although not shown, for example, for erbium (Er), when irradiated with light of 1120 nm and 1500 nm as excitation light, through an up-conversion process, at the energy level of Er ³⁺ ions, 660 nm ( ⁴ F _9/2 − ⁴ I _15/2 ) Red light emission.

  In the present embodiment, the phosphor particles may contain ytterbium (Yb). This is because ytterbium (Yb) has a good sensitivity to light and functions as a sensitizer.

  Here, a system using the above-described rare earth element that is excited by light of two or more different wavelengths and emits up-conversion light and ytterbium (Yb) will be described. When ytterbium is excited, energy is generated, and the energy generated by the excitation of ytterbium may be able to push up the energy level of the rare earth element in some cases. This is because energy transfer can occur when the energy level of ytterbium is close to the energy level of the rare earth element. Therefore, for example, when two types of excitation light having different wavelengths are used, one excitation light can be ytterbium excitation wavelength light, and the other excitation light can be excitation light of a rare earth element. In this case, since ytterbium has good sensitivity to light, it is possible to efficiently perform up-conversion light emission.

  When the phosphor particle dispersion of this embodiment is applied to a three-dimensional display device capable of color display, the phosphor particles exhibit a plurality of emission colors, or the phosphor particle dispersions are different from each other. It preferably contains a plurality of phosphor particles exhibiting a luminescent color. That is, it is preferable that the phosphor particle dispersion contains one kind of phosphor particles exhibiting a plurality of emission colors or a plurality of phosphor particles each exhibiting a single emission color.

  When the phosphor particles exhibit a plurality of luminescent colors, it is particularly preferable that the phosphor particles exhibit three primary colors of red, green, and blue. In this case, for example, a plurality of emission colors can be obtained by using phosphor particles containing a plurality of rare earth elements.

At this time, the plurality of rare earth elements contained in the phosphor particles are preferably excited by light of different wavelengths and emit up-conversion light. In the three-dimensional display device using the phosphor particle dispersion according to the present embodiment, the emission point is moved three-dimensionally, for example, by scanning two infrared lights, so that the up-conversion is excited by light of substantially the same wavelength. This is because if a plurality of rare earth elements that emit light are used, it is difficult to move the light emission points of the respective colors separately.
In order to excite one kind of rare earth element for upconversion emission, as described above, two or more kinds of infrared light having different wavelengths are irradiated, so that the excitation light used for upconversion emission of each rare earth element. It is preferable that the wavelengths are different from each other. Specifically, the difference is preferably ± 5 nm or more, more preferably ± 10 nm or more.

  On the other hand, in the case where the phosphor particle dispersion contains a plurality of phosphor particles exhibiting different emission colors, it is particularly preferable to contain phosphor particles respectively showing three primary colors of red, green, and blue emission colors. . In this case, for example, a plurality of emission colors can be obtained by forming a phosphor particle dispersion including phosphor particles each containing different rare earth elements.

  At this time, it is preferable that the rare earth elements contained in the respective phosphor particles are excited by light having different wavelengths and emit up-conversion light, as in the case described above. Note that the difference in wavelength of the excitation light is the same as described above.

  Thus, when the phosphor particle dispersion of this embodiment is applied to a three-dimensional display device capable of color display, the type of rare earth element is determined in consideration of the wavelength of the excitation light that causes the rare earth element to up-convert light emission. It is selected appropriately.

  The range of the wavelength of the excitation light that causes the rare-earth element to up-convert light emission is preferably in the infrared region, and is at least a wavelength in the range of 700 nm to 2000 nm, and more preferably in the range of 700 nm to 1800 nm, particularly 800 nm to 1600 nm. A wavelength within the range is preferred.

  Further, the base material used in the present embodiment is not particularly limited as long as it supports a rare earth element and supports the rare earth element in a state capable of up-conversion light emission. For example, it may be an organic substance that reacts with a rare earth element to form a complex, a dendrimer, or the like, or may be an inorganic substance. Among these, it is preferable to use an inorganic substance. This is because it is easy to contain a rare earth element in a state capable of emitting light, and high emission intensity can be obtained.

  As the inorganic base material, a material having transparency to excitation light is preferable from the viewpoint of luminous efficiency. Specifically, halides, oxides, sulfides and the like are preferably used, and halides are particularly preferably used. This is because the luminous efficiency is further improved when the base material of the phosphor particles is a halide.

Examples of the halide include chlorides such as lanthanum chloride (LaCl ₃ ), yttrium chloride (YCl ₃ ), barium chloride (BaCl ₂ ), lead chloride (PbCl ₂ ), lead fluoride (PbF ₂ ), and cadmium fluoride. Fluorides such as (CdF ₂ ), lanthanum fluoride (LaF ₃ ), and yttrium fluoride (YF ₃ ) can be used. A halide containing a different element such as yttrium / lanthanum fluoride can also be used.

  Among these, fluoride is preferable. This is because fluoride has a low phonon energy and is a base material suitable for upconversion light emission by two-stage absorption. In general, halides are unstable with respect to water and the like, but fluoride is the most stable among halides. As will be described later, since the transparent liquid or transparent resin is usually an organic substance, and the inorganic substance and the organic substance tend to have a higher refractive index, the phosphor particles are considered in consideration of the refractive index of the transparent liquid or transparent resin. The refractive index of is preferably relatively low. When the base material is fluoride, the refractive index tends to be lower than when the base material is chloride, and therefore fluoride is preferably used. Further, when the base material is a fluoride, the refractive index tends to be lower than when the base material is an oxide.

When a halide is used as the base material, it is preferable that a protective layer is formed around it. This is because halides are generally unstable with respect to water and the like, and if phosphor particles having halides as a base material are used as they are, images may not be displayed accurately. In such a case, it is preferable to form a composite core part by forming a coating material having water resistance around the phosphor particles having a halide as a base material. As this coating material, oxides such as yttrium oxide (Y ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), and tantalum oxide (Ta ₂ O ₅ ) can be suitably used. .

  In this embodiment, the base material of the phosphor particles is appropriately selected so that the refractive index of the phosphor particles and the refractive index of the transparent liquid or transparent resin are substantially the same.

  In general, the inorganic material and the organic material tend to have a higher refractive index. Further, as will be described later, the transparent liquid or transparent resin is usually an organic substance. Therefore, for example, when the base material of the phosphor particles is an inorganic substance, the phosphor particles tend to have a higher refractive index between the phosphor particles and the transparent liquid or transparent resin. Therefore, considering the refractive index of the transparent liquid or transparent resin, the refractive index of the phosphor particles is preferably relatively low.

Further, when a halide containing a different element is used as a base material, the refractive index of the phosphor particles can be adjusted by changing the blending ratio of the different element. For example, erbium-doped yttrium fluoride (Y _0.999, Er _0.001) refractive index of the F ₃ particles is about 1.53, erbium-doped lanthanum fluoride _{(La 0.999, Er 0.001) F} 3 Since the refractive index of the particles is about 1.60, the refractive index of the phosphor particles can be adjusted by using yttrium lanthanum fluoride as a base material and changing the blending ratio of yttrium and lanthanum.

The average particle diameter of the phosphor particles is not particularly limited, and for example, particles having a diameter of about 0.001 μm to 100 μm can be used.
The average particle diameter is a value obtained by extracting 100 phosphor particles from an electron micrograph such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and averaging the particle diameters.

Further, the content of the phosphor particles in the phosphor particle dispersion is not particularly limited. In general, the emission intensity decreases as the phosphor particle content decreases, and the emission intensity tends to increase as the phosphor particle content increases. However, if the content of the phosphor particles is too large, scattering is caused by the phosphor particles, which may reduce the emission intensity.
As described above, the content of the phosphor particles in the phosphor particle dispersion is appropriately adjusted according to the application of the present invention in consideration of the emission intensity of up-conversion emission.

  The method for synthesizing the phosphor particles is not particularly limited as long as the phosphor particles suitable for the object of the present invention can be obtained.

2. Transparent resin The transparent resin used in the present embodiment is not particularly limited as long as the phosphor particles can be dispersed, but it is preferable that the phosphor particles can be immobilized. . As such a transparent resin, any of a thermosetting resin, a thermoplastic resin, and a photocurable resin can be used. As these thermosetting resins, thermoplastic resins, and photocurable resins, those generally used can be used.

  Among these, a photocurable resin is preferable. In the case of using a photocurable resin, for example, the phosphor particles are dispersed in the photocurable resin by mixing the monomer used for forming the photocurable resin and the phosphor particles and then curing the monomer. A phosphor particle dispersion can be obtained. Therefore, when the transparent resin is a photocurable resin, the dispersibility of the phosphor particles in the transparent resin can be improved.

  The transparent resin is preferably optically transparent, and more preferably excellent in light stability and the like. Examples of such transparent resins include cycloolefin polymers, polymethyl methacrylate (PMMA), polycarbonate (PC), polystyrene (PS), and the like.

  In this embodiment, the transparent resin is appropriately selected so that the refractive index of the transparent resin and the refractive index of the phosphor particles are substantially the same. In this case, when the transparent resin is a photocurable resin or a thermosetting resin and a monomer is used as a raw material for the photocurable resin or the thermosetting resin, as described above, The fact that the refractive index and the refractive index of the transparent resin are substantially the same means that the refractive index of the phosphor particles and the refractive index of the monomer that is the raw material of the transparent resin are substantially the same. The monomer may be selected so that the refractive index and the refractive index of the phosphor particles are substantially the same.

  As described above, generally, the inorganic material and the organic material tend to have a higher refractive index. Moreover, organic substance is normally used as transparent resin. Therefore, for example, when the base material of the phosphor particles is an inorganic material, the phosphor particles tend to have a higher refractive index between the phosphor particles and the transparent resin. Therefore, considering the refractive index of the phosphor particles, the refractive index of the transparent resin is preferably relatively high.

  Moreover, when using transparent resin as transparent resin, the refractive index of transparent resin can be adjusted by changing the functional group which transparent resin has.

3. Transparent liquid The transparent liquid used in this embodiment is not particularly limited as long as it can disperse the phosphor particles. However, the dispersibility of the phosphor particles is good and affects upconversion emission. In particular, it is preferable that the emission intensity is not significantly reduced. An example of such a transparent liquid is a non-aqueous solvent. This is because the use of a non-aqueous solvent compared to an aqueous solvent can suppress a decrease in emission intensity due to the influence of the transparent liquid.

  Examples of the non-aqueous solvent include ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, and n-butanol; dichloroethyl ether, isopropyl ether, n- Ether solvents such as butyl ether; hydrocarbon solvents such as toluene and xylene; ester solvents such as ethyl acetate, acetic acid-n-propyl, isopropyl acetate, and acetic acid-n-butyl; ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether Polyhydric alcohol solvents such as propylene glycol monoethyl ether; Fluorine solvents such as HFE-7100 (trade name, manufactured by Sumitomo 3M), HFE-7200 (trade name, manufactured by Sumitomo 3M); Is mentioned. These non-aqueous solvents may be used alone or in combination of two or more.

  In the present embodiment, the transparent liquid is appropriately selected so that the refractive index of the transparent liquid and the refractive index of the phosphor particles are substantially the same.

  As described above, generally, the inorganic material and the organic material tend to have a higher refractive index. Moreover, an organic substance is usually used as the transparent liquid. Therefore, for example, when the base material of the phosphor particles is an inorganic substance, the phosphor particles tend to have a higher refractive index between the phosphor particles and the transparent liquid. Therefore, considering the refractive index of the phosphor particles, the refractive index of the transparent liquid is preferably relatively high.

4). Phosphor particle dispersion The phosphor particle dispersion of the present embodiment is preferably transparent. This is because if the phosphor particle dispersion is opaque, the display quality may deteriorate when used in a three-dimensional display device. Specifically, the average transmittance in the visible region of the phosphor particle dispersion is preferably 10% or more, more preferably 30% or more, and most preferably 70% or more.
In addition, let the said average transmittance | permeability be the average value of the value measured using Shimadzu Corporation Corp. UV-3100 within the wavelength range of 380 nm-800 nm.

  The phosphor particle dispersion of this embodiment can be applied to, for example, a display unit of a three-dimensional display device. Among these, the phosphor particle dispersion of the present embodiment is suitably used for the display unit of a three-dimensional display device. This is because the phosphor particle dispersion of the present embodiment has high transparency, so that a three-dimensional display device having excellent display quality can be obtained.

  In addition, the method for producing the phosphor particle dispersion of the present embodiment is appropriately selected depending on whether the phosphor particles are dispersed in a transparent resin or a transparent liquid.

  When the phosphor particle dispersion is formed by dispersing phosphor particles in a transparent resin, the phosphor particle dispersion can be obtained by mixing or kneading the phosphor particles in the transparent resin. Further, when the transparent resin is a photocurable resin or a thermosetting resin, the phosphor particles are dispersed in the monomer used for forming the photocurable resin or the thermosetting resin, and then the monomer is cured. A phosphor particle dispersion can be obtained. When the transparent resin is a photocurable resin or a thermosetting resin, an initiator or the like may be added to the monomer used for forming the photocurable resin or the thermosetting resin. In this case, it is preferable that the refractive index of the initiator has a relatively small difference between the refractive index of the phosphor particles and the refractive index of the transparent resin.

  Further, when the phosphor particles are dispersed in a transparent liquid, the phosphor particle dispersion can be obtained by dispersing the phosphor particles in the transparent liquid. The viscosity of the obtained phosphor particle dispersion is not particularly limited, and is appropriately adjusted according to the application of the present invention. When the phosphor particle dispersion of the present embodiment is applied to, for example, a three-dimensional display device, the viscosity of the phosphor particle dispersion is preferably a viscosity at which the phosphor particles are difficult to settle.

II. Second Embodiment In the second embodiment of the phosphor particle dispersion of the present invention, phosphor particles that emit up-conversion light when excited by light of one wavelength among wavelengths in the range of 700 nm to 2000 nm are transparent. A phosphor particle dispersion dispersed in a resin, wherein a refractive index of the phosphor particles and a refractive index of the transparent resin are substantially the same.

The up-conversion light emission in this embodiment will be described with reference to the drawings. FIG. 5 shows a system in which two types of ytterbium (Yb) and erbium (Er) are used, and an example in which infrared light of 980 nm is irradiated as excitation light is shown. First, as shown in FIG. 5A, ytterbium is excited by excitation light of 980 nm and moves from ² F _7/2 to ² F _5/2 having a higher energy level. Then, this energy, the energy transfer 1, the energy level of erbium, push up from ⁴ I _15/2 to ⁴ I _11/2. Then, as shown in FIG. 5 (b), similarly ytterbium is excited by the excitation light of 980 nm, this energy is the energy transfer 2, ⁴ further the energy levels of erbium from ⁴ I _11/2 F _11/2 Push up. Then, as shown in FIG. 5C, when the excited erbium returns to the ground state, light of 550 nm is emitted.

  As described above, in this embodiment, the case where the light excited at 980 nm emits light having a higher energy of 550 nm, that is, the case where light having higher energy than the excitation light is emitted is referred to as up-conversion light emission. is there.

  Since the phosphor particles in the present embodiment contain, for example, a rare earth element that generates such up-conversion light emission, it is not necessary to excite with high energy light such as ultraviolet light. In addition, when the phosphor particle dispersion according to this embodiment is used in, for example, a display device, it is usually preferable that light emission is visible light. Therefore, in the case of up-conversion emission, light having a wavelength longer than that of visible light is used as excitation light. For this reason, the excitation light wavelength and the emission wavelength hardly overlap each other, and a good image display can be obtained.

Further, the phosphor particles in the present embodiment emit up-conversion light when excited by light of one kind of wavelength. That is, the phosphor particles can be excited by one type of excitation light of the infrared light 4 having the wavelength λ ₄ and emit light having the wavelength λ ₅ as illustrated in FIG.
In this way, in this embodiment, up-conversion emission by two-stage absorption is referred to as a case where up-conversion emission is excited through an energy level by excitation light of one kind of wavelength.

FIG. 7 shows a two-dimensional display device using a phosphor particle dispersion in which phosphor particles exhibiting up-conversion emission exemplified in FIG. 6 are dispersed in a transparent resin. As illustrated in FIGS. 7A and 7B, infrared light 15 having a wavelength λ ₄ from one direction of the display unit 11 made of the phosphor particle dispersion according to the present embodiment (infrared light 4 in FIG. 6). Irradiate. Then, the portion irradiated with the infrared light 15 (infrared light 4 in FIG. 6) emits light. This is because up-conversion light emission illustrated in FIG. 6 occurs at this time. When the infrared light 15 is scanned in the horizontal and vertical directions, the light emitting portion moves in a plane, so that a two-dimensional image can be displayed. In the example shown in FIG. 7A, the surface of the display unit 11 irradiated with the infrared light 15 is the image display surface 20, and in the example shown in FIG. 7B, the infrared light 15 is irradiated. A surface perpendicular to the surface of the display unit 11 can be the image display surface 20.

  In this embodiment, since the refractive index of the phosphor particles and the refractive index of the transparent resin are substantially the same, the transparency of the phosphor particle dispersion can be improved. Therefore, when the phosphor particle dispersion according to this embodiment is used in, for example, a display device, display quality can be improved.

  Note that “the refractive index of the phosphor particles and the refractive index of the transparent resin are substantially the same”, “the refractive index of the transparent resin”, the method of measuring the refractive index of the phosphor particles, and the refractive index of the transparent resin. Since the measurement method is the same as that described in the first embodiment, description thereof is omitted here.

  Furthermore, the phosphor particle dispersion of the present embodiment is obtained by dispersing phosphor particles in a transparent resin. For example, the phosphor particles are kneaded into the transparent resin, or the phosphor particles are used to form a transparent resin. It can be produced by curing the monomer after dispersing it in the monomer or the like used. Therefore, it can be easily manufactured and can be increased in size.

  Further, in the case where the phosphor is deposited on the conventional glass, the medium on which the phosphor is deposited is limited. In the present embodiment, the transparent resin in which the phosphor particles are dispersed can be arbitrarily selected. It is possible to prevent the emission color from being affected by the composition of Therefore, it is possible to obtain a target emission color.

  In addition, about transparent resin, since it is the same as that of what was described in the said 1st embodiment, description here is abbreviate | omitted. Hereinafter, another configuration of the phosphor particle dispersion according to this embodiment will be described.

1. Phosphor particles The phosphor particles in the present embodiment are preferably so-called activated phosphor particles in which an element that emits fluorescence is doped into a base material. This is because the intensity and color of light emission can be adjusted depending on the type of element and the amount of doping.

  At this time, the fluorescent element contained in the phosphor particles can be excited by light of one wavelength and emit up-conversion light, and is excited by light of a wavelength within a predetermined range. It is not particularly limited as long as it is. This is because a two-dimensional display device using such a phosphor particle dispersion can display an image by utilizing the up-conversion phenomenon due to two-stage absorption of the phosphor particles.

  In this embodiment, the phosphor particles preferably contain a rare earth element. This is because the rare earth element can be up-converted by being excited by light of one wavelength.

  The rare earth element used in this embodiment is not particularly limited as long as it is excited by light of one kind of wavelength and emits up-conversion light. In general, rare earth elements that are trivalent ions can be mentioned, among which erbium (Er), holmium (Ho), praseodymium (Pr), thulium (Tm), neodymium (Nd), gadolinium (Gd), Europium (Eu), samarium (Sm), terbium (Tb), dysprosium (Dy) and cerium (Ce) are preferably used. These rare earth elements may be used alone or in combination of two or more.

  In the present embodiment, it is preferable that the phosphor particles contain ytterbium (Yb). This is because ytterbium (Yb) has a good sensitivity to light and functions as a sensitizer. In addition, as illustrated in FIG. 5, there are cases where the energy level of the rare earth element can be pushed up by the energy transfer caused by the excitation of ytterbium. This is because energy transfer can occur when the energy level of ytterbium is close to the energy level of the rare earth element. Therefore, it is possible to obtain up-conversion light emission by using light of one kind of wavelength, using light of the excitation wavelength of ytterbium as one kind of excitation light and utilizing the energy transfer of energy generated by the excitation of ytterbium. it can. In this case, since ytterbium has good sensitivity to light, it is possible to efficiently perform upconversion light emission.

  In addition, the range of the wavelength of excitation light that causes up-conversion emission of rare earth elements, the base material, the average particle diameter of the phosphor particles, the content of the phosphor particles in the phosphor particle dispersion, and the method for synthesizing the phosphor particles Is the same as that described in the first embodiment, and a description thereof will be omitted here.

2. Phosphor particle dispersion The phosphor particle dispersion of the present embodiment is preferably transparent. This is because if the phosphor particle dispersion is opaque, the display quality may deteriorate when used in a two-dimensional display device.
Since the average transmittance in the visible region of the phosphor particle dispersion is the same as that described in the first embodiment, description thereof is omitted here.

  In addition, when the phosphor particle dispersion of this embodiment is used in, for example, a two-dimensional display device, the thickness of the phosphor particle dispersion is appropriately selected according to the application. When the thickness is relatively thin, it is possible to make a flexible display device, which can be reduced in weight and size. Further, the display device can be manufactured by roll-to-roll, so that productivity is improved. There is an advantage of doing. When the thickness is made relatively thin, the phosphor particle content in the phosphor particle dispersion may be made relatively high in order to obtain a desired luminance.

The phosphor particle dispersion may be formed on a substrate. When the phosphor particle dispersion is formed on a substrate, the strength and weather resistance can be increased. In addition, when the phosphor particle dispersion is formed on the substrate, the thickness of the phosphor particle dispersion can be made relatively thin.
Furthermore, the phosphor particle dispersion may be sandwiched between two substrates.

As a base material, it is preferable that the transmittance | permeability in an infrared region, specifically, the transmittance | permeability in the range of 700 nm-2000 nm is comparatively high. Examples of such a substrate include polyethylene terephthalate (PET).
Further, the thickness of the substrate is appropriately selected according to the application.

The phosphor particle dispersion of this embodiment is suitably used for a display unit of a two-dimensional display device. This is because the phosphor particle dispersion of the present embodiment has high transparency, so that a two-dimensional display device having excellent display quality can be obtained.
When the phosphor particle dispersion is used in the display unit of the two-dimensional display device, the form of the phosphor particle dispersion can be a screen or the like.

  In addition, since the manufacturing method of the phosphor particle dispersion is the same as that described in the first embodiment, description thereof is omitted here.

B. 3D Display Device Next, the 3D display device of the present invention will be described. A three-dimensional display device according to the present invention includes a display unit having the above-described phosphor particle dispersion, two or more infrared light sources arranged around the display unit, and light emitted from the infrared light source. And a control means for controlling the direction.

  FIG. 3 shows an example of the three-dimensional display device of the present invention. As shown in FIG. 3, the three-dimensional display device 10 of the present invention includes a display unit 11 made of a phosphor particle dispersion and two infrared light sources 12a and 12b arranged around the display unit 11. is doing. The infrared light sources 12a and 12b emit infrared light 15a and 15b having different wavelengths. Furthermore, the infrared light sources 12a and 12b are movable, and the direction of the infrared light 15a and 15b can be arbitrarily changed. In the three-dimensional display device 10, the means for moving the infrared light sources 12a and 12b is a control means for controlling the directions of the infrared lights 15a and 15b.

  When the infrared light 15a and 15b are irradiated to the display unit 11 from different directions by the infrared light sources 12a and 12b and the infrared light 15a and the infrared light 15b are crossed, the crossed point 13 emits light. This is because the phosphor particles in the phosphor particle dispersion are excited by the infrared light 15a and 15b having different wavelengths, that is, excited by two-stage absorption as shown in FIG. Since the infrared light sources 12a and 12b are movable, the infrared light sources 12a and 12b are moved, and scanning in the horizontal and vertical directions while synchronizing the infrared light 15a and 15b is performed in the display unit 11. The light emitting point 13 can be moved back and forth, left and right, and up and down. Thereby, in the present invention, a stereoscopic image can be displayed.

  In the present invention, since the phosphor particle dispersion described above is used for the display unit, it is excellent in transparency and display quality can be improved. Further, the display unit can be easily enlarged. Furthermore, since this phosphor particle dispersion can arbitrarily select the medium in which the phosphor particles are dispersed, it can be avoided that the emission color is influenced by the composition of the medium.

Further, in the case of a three-dimensional display device capable of color display, it is necessary to prepare a phosphor particle dispersion so that a plurality of emission colors can be obtained. In the present invention, a plurality of phosphor particles are used as a medium. Since the phosphor particle dispersion can be obtained simply by dispersing the particles, it is possible to easily obtain the display unit of the three-dimensional display device capable of color display.
Hereinafter, each configuration of the three-dimensional display device of the present invention will be described.

1. Display unit The display unit used in the present invention has a phosphor particle dispersion.

When the phosphor particle dispersion is formed by dispersing the phosphor particles in a transparent liquid, the phosphor particle dispersion itself is in a liquid state, so that the display unit usually has the phosphor particle dispersion in the cell. It will be filled.
At this time, the cell used for filling the phosphor particle dispersion is not particularly limited as long as it does not affect the up-conversion emission, specifically, the emission intensity is not significantly reduced. Absent. Further, the cell is preferably transparent, and specifically, it is preferable that the average transmittance in the visible region is relatively high. Examples of such a cell include a glass cell, a quartz cell, and a plastic cell.

  On the other hand, when the phosphor particle dispersion is one in which the phosphor particles are dispersed in a transparent resin, the phosphor particle dispersion itself is in a solid state. It becomes.

  The size of the display unit is not particularly limited, and is appropriately selected depending on the application.

2. Infrared light source At least two infrared light sources are required for the present invention, and are arranged around the display unit to emit infrared light.

  The number of infrared light sources is not particularly limited as long as it is two or more. In the present invention, since the phenomenon of up-conversion light emission due to excitation by two-stage absorption is often used, for example, two infrared light sources are required to obtain light emission of one color, and light emission of three colors is obtained. For this purpose, six infrared light sources are required. This infrared light source emits only infrared light having one wavelength.

  Further, the light source is not particularly limited as long as it emits infrared light, and for example, a semiconductor laser or the like can be used. For example, as shown in FIG. 8, the infrared light sources 12a and 12b may be a laser array in which a plurality of semiconductor lasers are arranged in an array.

  Moreover, since the three-dimensional display device of the present invention emits the intersection 13 of each infrared light 15a, 15b emitted from two infrared light sources 12a, 12b, for example, as shown in FIG. It is preferable to arrange the infrared light sources 12a and 12b so that the directions of the infrared lights 15a and 15b are not linear. This is because when the directions of the infrared light 15a and 15b are in a straight line, the portion where the infrared light 15a and 15b intersect emits light, and thus light emission is observed in a linear shape. Therefore, when scanning in the horizontal and vertical directions while synchronizing the infrared lights 15a and 15b, it is preferable to scan so that the directions of the infrared lights 15a and 15b are not in a straight line.

3. Control Unit The control unit in the present invention is not particularly limited as long as it controls the direction of light emitted from the infrared light source. The control means may control the directions of the infrared light 15a and 15b by moving the infrared light sources 12a and 12b as shown in FIG. 3, for example, and for example, as shown in FIG. The mirrors 16a and 16b may be disposed in the vicinity of the light sources 12a and 12b, and the directions of the infrared lights 15a and 15b may be controlled by changing the angles and positions of the mirrors 16a and 16b.

C. 2D Display Device Next, the 2D display device of the present invention will be described. The two-dimensional display device of the present invention controls a display unit having the above-described phosphor particle dispersion, an infrared light source that projects infrared light onto the display unit, and a direction of light emitted from the infrared light source. And a control means.

  FIG. 7 shows an example of the two-dimensional display device of the present invention. As shown in FIGS. 7A and 7B, the two-dimensional display device of the present invention includes a display unit 11 made of a phosphor particle dispersion and an infrared light source 12 that projects infrared light onto the display unit 11. And have. The infrared light source 12 is movable, and the direction of the infrared light 15 can be arbitrarily changed. In this two-dimensional display device, the means for moving the infrared light source 12 is a control means for controlling the direction of the infrared light 15.

  When the infrared light 15 is applied to the display unit 11 from a predetermined direction by the infrared light source 12, the irradiated part emits light. This is because the phosphor particles in the phosphor particle dispersion are excited by the infrared light 15, that is, excited by two-stage absorption as shown in FIG. Since the infrared light source 12 is movable, the infrared light source 12 is moved, and the infrared light 15b is scanned in the horizontal and vertical directions so that the light emitting portion is moved back and forth, left and right, and up and down in the display unit 11. Can be moved. Thereby, the display of an image is attained in this invention.

  In the present invention, since the phosphor particle dispersion described above is used for the display unit, it is excellent in transparency and display quality can be improved. Further, the display unit can be easily enlarged. Furthermore, since this phosphor particle dispersion can arbitrarily select the medium in which the phosphor particles are dispersed, it can be avoided that the emission color is influenced by the composition of the medium.

  Note that the control means can be the same as the control means in the three-dimensional display device, and a description thereof will be omitted here. Hereinafter, another configuration of the two-dimensional display device of the present invention will be described.

1. Display unit The display unit used in the present invention has a phosphor particle dispersion.
The phosphor particle dispersion is obtained by dispersing phosphor particles in a transparent resin, and the phosphor particle dispersion itself is in a solid state. Therefore, the phosphor particle dispersion itself may be a display unit. Further, as described above, the phosphor particle dispersion may be formed on a base material or may be sandwiched between two base materials.

  The size of the display unit is not particularly limited, and is appropriately selected depending on the application.

2. Infrared light source The infrared light source used in the present invention projects infrared light on the display unit, and is arranged around the display unit.

The number of infrared light sources may be one or more.
Since the other points of the infrared light source are the same as those of the infrared light source in the three-dimensional display device, description thereof is omitted here.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

[Example 1]
1. _{(Y 0.999, Er 0.001) F} 3 Synthesis Y99.9Mol% of particles and Er0.01Mol% and fluoride blended with (Y _0.999, Er _0.001) were prepared F ₃ particles. The SEM and XRD measurement results confirmed that it was (Y _0.999 , Er _0.001 ) F ₃ particles.
The refractive index of this (Y _0.999 , Er _0.001 ) F ₃ particle was measured by the measurement method described above and found to be about 1.53.

2. (Y _0.999 , Er _0.001 ) Preparation of F ₃ Particle Dispersion As the transparent resin, a cycloolefin polymer (ZEONEX E48R manufactured by Nippon Zeon Co., Ltd.) was used. The refractive index of this cycloolefin polymer measured by the measurement method described above was about 1.53.
100 g of the synthesized (Y _0.999 , Er _0.001 ) F ₃ particles and 900 g of cycloolefin polymer were kneaded to prepare a compound (kneaded pellets of (Y _0.999 , Er _0.001 ) F ₃ particles and cycloolefin polymer).
The produced compound was injection-molded to produce a 1 cm square transparent resin molded body (phosphor particle dispersion).

3. Evaluation The transparent resin molded body thus obtained was irradiated so that two kinds of infrared lasers 1 and 2 intersected. A semiconductor laser having a wavelength of about 1540 nm was used for the infrared light laser 1, and a semiconductor laser having a wavelength of about 840 nm was used for the infrared light laser 2. As a result, green emission of Er ³⁺ near 550 nm was observed at the intersection of the infrared laser 1 and the infrared laser 2.

[Example 2]
1. _{(La 0.999, Er 0.001) F} 3 Synthesis La99.9Mol% of particles and Er0.01Mol% and fluoride blended with (La _0.999, Er _0.001) were prepared F ₃ particles. From the measurement results of SEM and XRD, it was confirmed to be (La _0.999 , Er _0.001 ) F ₃ particles.
The refractive index of this (La _0.999 , Er _0.001 ) F ₃ particle was measured by the measurement method described above, and it was about 1.60.

2. Production of (La _0.999 , Er _0.001 ) F ₃ Particle Dispersion Polystyrene (manufactured by PS Japan) was used as the transparent resin. When the refractive index of this polystyrene was measured by the measurement method described above, it was about 1.60.
100 g of the synthesized (La _0.999 , Er _0.001 ) F ₃ particles and 900 g of polystyrene were kneaded to produce a compound ((La _0.999 , Er _0.001 ) F ₃ particles and polystyrene kneaded pellets).
The produced compound was injection-molded to produce a 1 cm square transparent resin molded body (phosphor particle dispersion).

3. Evaluation The transparent resin molded body thus obtained was irradiated so that two kinds of infrared lasers 1 and 2 intersected. A semiconductor laser having a wavelength of about 1540 nm was used for the infrared light laser 1, and a semiconductor laser having a wavelength of about 840 nm was used for the infrared light laser 2. As a result, green emission of Er ³⁺ near 550 nm was observed at the intersection of the infrared laser 1 and the infrared laser 2.

[Comparative example]
1. _{(Y 0.999, Er 0.001) F} 3 Synthesis Y99.9Mol% of particles and Er0.01Mol% and fluoride blended with (Y _0.999, Er _0.001) were prepared F ₃ particles. The SEM and XRD measurement results confirmed that it was (Y _0.999 , Er _0.001 ) F ₃ particles.
The refractive index of this (Y _0.999 , Er _0.001 ) F ₃ particle was measured by the measurement method described above and found to be about 1.53.

2. (Y _0.999 , Er _0.001 ) Preparation of F ₃ Particle Dispersion Polymethyl methacrylate (Sumipex) was used as the transparent resin. With respect to this polymethyl methacrylate, the refractive index was measured by the measurement method described above, and it was about 1.49.
100 g of the synthesized (Y _0.999 , Er _0.001 ) F ₃ particles and 900 g of polymethyl methacrylate were kneaded to prepare a compound (kneaded pellets of (Y _0.999 , Er _0.001 ) F ₃ particles and polymethyl methacrylate).
The produced compound was injection-molded to produce a 1 cm square transparent resin molded body (phosphor particle dispersion).

3. Evaluation The obtained transparent resin molding was cloudy and was difficult to use as a display part of a three-dimensional display device.

[Example 3]
1. _{(Y 0.99, Er 0.01) F} 3 particles synthesized Y99mol% and Er1mol% and fluoride blended with the (Y _0.99, Er _0.01) were prepared F ₃ particles. From the SEM and XRD measurement results, it was confirmed to be (Y _0.99 , Er _0.01 ) F ₃ particles.
The refractive index of this (Y _0.99 , Er _0.01 ) F ₃ particle was measured by the measurement method described above, and it was about 1.53.

2. Production of phosphor particle dispersion Transparent resins include TMMP (trimethylolpropane tris-3-mercaptopropionate, refractive index 1.52) manufactured by Sakai Chemical Industry, and Aronix A-211B (bisphenol EO modified) manufactured by Toagosei Co., Ltd. (N≈2) Diacrylate, refractive index 1.536) was used. These transparent resins were mixed at a weight ratio of 2: 3 (TMMP: Aronix A-211B), 10 wt% (Y _0.99 , Er _0.01 ) F ₃ particles were dispersed with a stirrer, and Irgacure-184 ( 1-Hydroxy-cyclohexyl-phenyl-ketone, refractive index 1.529) was used to prepare a mixed resin. A mixed resin was poured onto a PET film (125 μm thick, Toyobo A4300), and a 1 cm square transparent resin molding (phosphor particle dispersion) was produced by UV curing. In addition, it was about 1.54 when the refractive index after UV hardening of the said mixed resin was measured with the Abbe refractometer NAR-1T SOLID by an Atago company.

3. Evaluation The transparent resin molded body thus obtained was irradiated so that two kinds of infrared lasers 1 and 2 intersected. A semiconductor laser having a wavelength of about 1540 nm was used for the infrared light laser 1, and a semiconductor laser having a wavelength of about 840 nm was used for the infrared light laser 2. As a result, green emission of Er ³⁺ near 550 nm was observed at the intersection of the infrared laser 1 and the infrared laser 2.

[Example 4]
1. _{(Y 0.81, Er 0.01, Yb} 0.18) F 3 Synthesis Y81mol% and Er1mol% and Yb18mol% and fluoride blended with particles _{(Y 0.81, Er 0.01, Yb} 0.18) were prepared F ₃ particles. From the SEM and XRD measurement results, it was confirmed to be (Y _0.81 , Er _0.01 , Yb _0.18 ) F ₃ particles.
When the refractive index of the (Y _0.81 , Er _0.01 , Yb _0.18 ) F ₃ particles was measured by the measurement method described above, it was about 1.53.

2. Production of phosphor particle dispersion Transparent resins include TMMP (trimethylolpropane tris-3-mercaptopropionate, refractive index 1.52) manufactured by Sakai Chemical Industry, and Aronix A-211B (bisphenol EO modified) manufactured by Toagosei Co., Ltd. (N≈2) Diacrylate, refractive index 1.536) was used. These transparent resins were mixed at a weight ratio of 2: 3 (TMMP: Aronix A-211B), and 10 wt% (Y _0.81 , Er _0.01 , Yb _0.18 ) F ₃ particles were dispersed with a stirrer, and Irgacure as a photopolymerization initiator. A mixed resin was prepared using -184 (1-hydroxy-cyclohexyl-phenyl-ketone, refractive index 1.529). A mixed resin was poured onto a PET film (125 μm thick, A4300 manufactured by Toyobo Co., Ltd.), and a phosphor particle dispersion having a thickness of 1.0 mm (including the thickness of the PET film) was prepared by UV curing. In addition, it was about 1.54 when the refractive index after UV hardening of the said mixed resin was measured with the Abbe refractometer NAR-1T SOLID by an Atago company.

3. Evaluation The phosphor particle dispersion obtained in this manner was irradiated with a semiconductor laser having a wavelength of about 980 nm, and green light emission of about 550 nm was observed.

It is explanatory drawing for demonstrating upconversion light emission. It is explanatory drawing for demonstrating upconversion light emission. It is a perspective view which shows an example of the three-dimensional display apparatus of this invention. It is explanatory drawing for demonstrating upconversion light emission. It is explanatory drawing for demonstrating upconversion light emission. It is explanatory drawing for demonstrating upconversion light emission. It is a schematic diagram which shows an example of the two-dimensional display apparatus of this invention. It is a perspective view which shows the other example of the three-dimensional display apparatus of this invention. It is a perspective view which shows the other example of the three-dimensional display apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Three-dimensional display device 11 ... Display part 12, 12a, 12b ... Infrared light source 15, 15a, 15b ... Infrared light

Claims (12)

The phosphor particles that are excited by light having a wavelength in the range of 700 nm to 2000 nm to emit up-conversion light are dispersed in a transparent liquid or transparent resin,
A phosphor particle dispersion, wherein the refractive index of the phosphor particles and the refractive index of the transparent liquid or transparent resin are substantially the same.   2. The phosphor according to claim 1, wherein the phosphor particles emit up-conversion light when excited by light having two or more different wavelengths among wavelengths in the range of 700 nm to 2000 nm. Particle dispersion.   The phosphor particle dispersion according to claim 2, wherein the phosphor particles contain a rare earth element, and a base material of the phosphor particles is a halide.   The rare earth elements are erbium (Er), holmium (Ho), praseodymium (Pr), thulium (Tm), neodymium (Nd), gadolinium (Gd), europium (Eu), samarium (Sm), terbium (Tb), The phosphor particle dispersion according to claim 3, wherein the phosphor particle dispersion is at least one rare earth element selected from the group consisting of dysprosium (Dy) and cerium (Ce).   The phosphor particle dispersion according to any one of claims 2 to 4, wherein the phosphor particle dispersion is used in a display unit of a three-dimensional display device.   2. The phosphor particle dispersion according to claim 1, wherein the phosphor particles are excited by light of one wavelength among wavelengths in the range of 700 nm to 2000 nm to emit up-conversion light. body.   The phosphor particle dispersion according to claim 6, wherein the phosphor particles contain a rare earth element, and a base material of the phosphor particles is a halide.   The rare earth elements are erbium (Er), holmium (Ho), praseodymium (Pr), thulium (Tm), neodymium (Nd), gadolinium (Gd), europium (Eu), samarium (Sm), terbium (Tb), The phosphor particle dispersion according to claim 7, wherein the phosphor particle dispersion is at least one rare earth element selected from the group consisting of dysprosium (Dy) and cerium (Ce).   The phosphor particle dispersion according to claim 8, wherein the phosphor particles further contain ytterbium (Yb).   The phosphor particle dispersion according to any one of claims 5 to 9, wherein the phosphor particle dispersion is used in a display unit of a two-dimensional display device.   A display unit having the phosphor particle dispersion according to claim 2, two or more infrared light sources arranged around the display unit, and the infrared light source. And a control means for controlling the direction of the light.   A display unit having the phosphor particle dispersion according to claim 6, an infrared light source that projects infrared light on the display unit, and light emitted from the infrared light source And a control means for controlling the direction.

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